This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Hepatitis C virus (HCV) infection is a major, global health problem and a leading cause of chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. The HCV p7 protein is a small integral membrane protein of 63 amino acids which oligomerizes and forms cation-selective pores. It has recently been demonstrated that p7 ion channel activity is required for the effective assembly and release of nascent HCV virions [1]. There is no crystal structure of p7, however, models based on experimental data have been explored. The p7 monomer forms two antiparallel transmembrane segments connected by a conserved cytosolic charged loop region, with both the N- and C-termini facing the lumen of the endoplasmic reticulum [2]. p7 oligomers have been observed in both heptameric and hexameric forms [3, 4, 5], and several hypothetical models of the p7 complex based on secondary-structure predictions have been reported [6, 3, 5, 7]. Most recently, a low-resolution cryo- EM map of p7 in a short-tail lipid environment (DHPC) by Luik et al. revealed a flower-like hexameric structure [5].